CODEWITHSUNDEEP
meteor
MickaelFM
MickaelFM

Reputation: 907

Meteor :read Session keys and be reactive

I have a Meteor helper that is not reactive. How do I detect that a new key has been added to Session so my helper will rerun ?

  'sessions': function() { // FIXME: not reactive
    return _.keys(Session.keys).sort();
  }

Thanks ! :)

Edit: I know that Session itself is reactive. But the keys of the Session dictionary is not. I would like to be able to detect that a new Session key has been added.

Upvotes: 2

Views: 88

Answers (1)

MasterAM
MasterAM

Reputation: 16488

You can achieve this by using Tracker.

The Session is an instance of ReactiveDict, and does not have a way of "subscribing" to all of the keys.

Implementing this involves overriding the original set() method by monkey-patching.

One way of doing this is by creating a Tracker dependency for the entire dict and invalidating it every time a key is set:

import { Tracker } from 'meteor/tracker';
import { Session } from 'meteor/session';

const originalSet = Session.set;
Session.keyDependendy = new Tracker.Dependency();

Session.set = function() {
  originalSet.apply(this, arguments);
  this.keyDependendy.changed();
}

// in your helper
'sessions': function() {
  Session.keyDependendy.depend();
  return _.keys(Session.keys).sort();
}

You can also make it more general by patching ReactiveDict's prototype.

Upvotes: 1

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